(a) Field of the Invention
The present invention relates to a tripod, and more particularly to a mini tripod that provides a considerable supporting force for supporting a photographic apparatus, that allows for easy and quick adjustment, and that is compact to carry and store.
(b) Description of the Prior Art
In general, the structure of a mini tripod is as that shown in FIG. 1. It essentially comprises a platform A1 for mounting lockably a photographic apparatus thereon, a substantially hollow frame A3, and a plurality of movable legs A2. A lower end of the platform A1 is connected to a spherical connector A11 to enable the connector A11 to be accommodated within the frame A3. The frame A3 is provided with an urging block A5 that has a nest shaped upper surface that can be in contact with the connector A11. One lateral side of the frame A3 is formed with a screw hole in a suitable position for passage of a rotary rod A4. The rotary rod A4 has a rear end shaped substantially like a conic adapted to contact a lower end of the urging block A5. In use, the rotary rod A4 is driven into or out of the frame A4. As the rear end of the rotary rod A4 is conical and is in contact with the lower end of the urging block A5, when the rotary rod A4 is turned outwardly, the urging block A5 will lower, causing the connector A11 connected to the lower end of the platform A1 to come to a movable state, thus allowing adjustment of the position of the photographic apparatus B thereon. When the rotary rod A4 is driven into the frame A3, the urging block A5 will be urge upwardly due to the conical rear end of the rotary rod A4, thereby causing the connector A11 to be clamped between the frame A3 and the urging block A5 in a secure manner. However, in this method that utilizes pressure to achieve positioning, the movable members are prevented from free movement totally by the utilization of friction. For relatively light photographic apparatus, the above-described structure can provide a certain securing function. However, for heavy (or precision) photographic apparatus, the securing effect is not very satisfactory. Oftentimes, because the weight of the photographic apparatus is far greater than the friction the tripod relies upon for securing purposes, the adjusted photographic angle or position may alter. And when the user wishes to re-adjust the angle or Position, he needs to apply a greater force to turn the rotary rod A4 inwardly into the frame A3 in order to obtain a greater securing frictional force. Upon a period of use, the urging block A5 and the conical rear end of the rotary rod A4 will wear, which leads to still smaller securing frictional force. Reduced securing friction means that a still greater force to turn the rotary rod A4. Thc consequence of such a vicious cycle is short service life of the tripod.